Rib elements located in the sealing rim region of a polygon shape all glass sealed beam headlamp are known to improve various characteristics of the hermetic seal formed when the lens and reflector members are thermally sealed together after assembly by melting the glass material. For example, there is disclosed in U.S. Pat. No. 4,128,864, which is assigned to the assignee of the present invention non-continuous rib elements projecting rearwardly from the back sealing surfaces of the individual lens and reflector members which resist deformation when the fusion seal is made. Continuous rib elements located on the front sealing surfaces of a polygon shape fusion sealed headlamp are also now employed in conventional manufacture whereupon a single rib element protrudes from the reflector member to physically engage the inner edge of the planar sealing surface located on the lens member to provide alignment when these lamp components are assembled for the heat sealing step.
On the other hand, discontinuous rib elements are now employed in the sealing rim region of an all glass polygon shaped headlamp unit when the seal between the lens and reflector members is accomplished with an adhesive. For example, there is disclosed in U.S. Pat. No. 4,544,998, also assigned to the assignee of the present invention, a plurality of rib elements extending forwardly from the front sealing surfaces of a reflector member and limited to corner locations which physically engage the inner edge of the planar sealing surface located on the lens member. As therein disclosed, said rib elements provide alignment means to position the lens and reflector members during the adhesive sealing step. A different type sealing engagement for adhesively sealed headlamp units of this general type is disclosed in U.S. Pat. No. 4,447,862, also assigned to assignee of the present invention. Corner rib elements project forwardly from the planar sealing surface of the lens member in said arrangement to physically engage the ends of discontinuous planar sealing surfaces located on the reflector member.
Such use of dissimilar sealing engagement means for this headlamp construction depending upon the sealing method being used understandably creates logistic problems for the lamp manufacturer as well as increases equipment costs to produce the different lamp parts. Additionally, rejection rates for the conventional pressed glass parts and the lamps produced therefrom are too high as a result of the warp, lack of alignment and void spaces being experienced in the finished glass seal during conventional lamp manufacture.
It would be desirable, therefore, to correct all of the above indicated drawbacks with a single headlamp construction utilizing lens and reflector members which are capable of being alternately sealed together with an adhesive as well as fusion sealed together.
It is another important object of the present invention to modify the sealing rim region of a polygon shaped glass sealed beam headlamp in such a manner that still other steps in the overall lamp manufacture are benefited than simply achieving in the desired hermetic seal in the assembled lamp construction such as a sealing rim profile on the individual lens and reflector members enabling said lamp components to be initially pressed with greater reliability.